A drive system for rotating a wheel of an aircraft landing gear is shown in WO-A-2014/023939 and WO-A-2014/023941. The drive system comprises a drive pinion; a motor operable to rotate the drive pinion via a drive path; and a driven gear adapted to be attached to the wheel so as to be capable of rotating the wheel, wherein the drive system has a drive configuration in which the drive pinion is capable of meshing with the driven gear to permit the motor to drive the driven gear via the drive path.